Protective device



Jan. 16, 1951 E. KOLISCH PROTECTIVE DEVICE Filed Aug. 9, 1947 VENTOR. Emil Kolzisch 5 7i WMWW ATT Nays.

Patented Jan. 16, 1 951 PROTECTIVE DEVICE Emil Kolisch, New York, N. Y., assignor, by die,

root and mesne assignments, to (iontinental Silver (30., Inc., Brooklyn, N. Y., a corporation of New York Application August '9, 1947, Serial No. 787,688

14 Claims. (Cl. 21944) This invention relates to protective devices, more especially for electrical appliancesof the type used in the home or in the oilices of physicians and dentists and particularly to a device which breaks the circuit when the appliance is verheated and may be readily reset to opera- -;tiveness and, though applicable to heaters for water, liquids or fluids generally, suchias for sterilization or for culinary purposes, is shown herein applied-to a. coffee percolator. j' It is among the objects of the invention to provide a protective device for an electrical heating appliance of the above type which is of simple, relatively inexpensive, compact and rugged construction, which does notfdetract from the normal operation of the appliance, ;'which is not exposed to contact with the matej rials to be heated by the appliancezandwhich yet may be completely concealed 1rom the exter ior of the appliance, which williunction to interruptthe circuit upon overheating of the appliance as for instance, in the absence of desired liquid therein, which functions without app eciable arcing both in maintaining the circuit in use and in interrupting the circuit upon overheating, and which admits of being instantly and unerringly restored to operativeness by the unskilled user by resort to a simple manipulation, such as the turn of a knob accessible from need for any tools for disassembly, or for reaching into the interior of the device.

It is a ieature of the invention to provide a plurality of fusible links of whichone only is maintained in operative position where it is subjected to the heat evolved in the appliance, the remaining fusible links being in reserve for ready replacement upon fusing of the link in use under excessive heat. To this end the fuse link in action is in engagement with a stop or contact in eilective heat conducting relationship with the heating element of the appliance. The stop and the fusible link are relatively displaceable, preferably by a manual member accessible from the exterior, such as for instance from the bot tom of the appliance for readily replacing a used link with a reserve link. Preferably each link is mounted on the free end of a spring armand the stop member has associated therewith,

an, psrtthereor, a camming the exterior of the appliance and without the along line 44 of Fig. 2,

guide to deiiect the into engagement with the stop and at the same time to stress the spring arm so thati'upon softening of the fusible link in action under excessive heat, the same will readily be ruptured; under the stress of the spring arm to sever the link and cause disengagement from the stop. In a preferred construction the fusible links radiate from a rotatable mount which de'' sirably risesirom the bottom of the device and to which is affixed the manually operated knob, while the stop is aifixed thereabovewith its associated cam-guide. While, the electrical circuit may extencjlthroughthe fusible link, it is withinthe scope oi the invention from its broader aspects to -havehthe electrical circuit by-pass the fusible link but to be automatically opened by the spring' release action upon severing of the fusible link, Q H. l

Anotheriieat ,e of the invention is the provi-. sion of means on the-rotatable mount to enable it to rotetefi only in one direction, thereby ensuring that the link will properly engage the cam guide so that it may be deflected into engage: ment with the contact. 1 Inthe accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,

Fig. Us a fragmentary perspective view of the electrical appliance,

Fig. 2 is a cross sectional view taken along line 2-2 of Fig. 1,

Fig. 3 is a cross sectional viewrtaken along line 3 -3ofFig.2,' i I Fig. 4 is a view partly in cross sectio taken Fig. 5 is a perspective view of the cam guide and contact, v

Fig. 6 is; a dropped perspective view on a smaller scale showing the heating element and mount therefor, and

Fig. '2 is a fragmentary perspective view on a smaller scale of another embodiment of the in-- vention.

Referring now to the'drawings there is shown a preferred embodiment of the protective device as applied to a cofiee percolator Hi. The latter comprises a container ll amxed to a hollow base H which has a'botto n plate l3 affixed thereto by means of screws ll whicli'pass through the bottom rim 150! the baseand are threaded into corresponding openings I6 in the upturned peripheral rim I! of the bottom plate l3.

Carried by the top I8 and extending through an opening |9 therein is a generally cylindrical, preferably ceramic mount 22. A cylindrical protective housing encompasses that portion of the mount which protrudes above top l8 and has an inturned rim 2| extending under diametrically opposed laterally extending cars 23 integral with the mount 22. To permit assembly of the housing 20 to the mount, the rim 2| may have diametrically opposed slots llfv to'accommodate said cars 23 so that upon slight rotation of the housing 20, after introduction of the cars into the slots 2|, the housing is attached relative to the mount. A nut 24 secured upon the threaded lower end 25 of the mount 22 causes the ears 23 to be pressed against the inturned rim 2| of the housing, rigidly to clamp thehousing and the mount to the base.

A high resistance wire 28 is wound around the upper end 26 of the mount 22 which is of slightly reduced diameter forming an annular ledge 21.. One end 29'of the wire is connected to the head of a bolt 30 which extends through a bore 3| in the ledge 2! and the mount 22,'and protrudes from the bottom of the --mount as at"32 being retained therein by a nut 33. The other end 34 of the resistance wire-28 passes through a bore 35 in the ledge 21' and mount '22 and extends from the bottoni of'the-mount as at 36 and is connected by a lead 31 to-a terminal plug 38 rigidly aflixed.

to an insulating plate-39 mountedon thewall of the base |2 as is the companion terminal plug 40.

The protective device disposed within the hollow base l2 "establishesanelectric circuit from the two ends 29 and 34 of'the heating coil to the -two terminals '38 and 40 respectively. This deend of the cam guide.

vice includes a pluralityof fusible links 6| 'each carried by a corresponding contact arm 59. An

electrical contact clos'e's" circuit to one only of said arms. The ruptureof the fusible link under excessive heat results" in automatic interruption of the electric circuit, preferably under release of stress resiliently imposed in"operative"position. The contact andthe fusible links are then relatively displace'able 'by manual'ac'tionv to restore the circuit." It is, of course',iiot' necessary that the entire length of the link b'e-o'f fusible materiall but only a portion thereof need be in order to break the circuit when such-"fusible portion ruptures;

The embodiment of the protective device herein chosento illustrate my invention comprises a cam guide 4| of heat conducting metal such as sheet metal having a curved cam arm 42 with a bend 43 therein and preferably having a sub stantially U-shaped contact or stop portion 44 at one end thereof which is'p'referably substantially squarein cross section. An arin"45 unitary with the cam guide 4| extends at substantially right angles thereto and is affixed to the bottom end of bolt 30 by a nut '46-, as shown in Figs. 2, 4 and5.

Mounted on bottom plate1|3 within the base is a rotatable mount comprisinga ci rcular block 41 of insulating material and a substantially cup shaped carrier 48 of metal. The cup -sh ape'd carrier 48 is affixed to the upper surface of the block, preferably by means of rivets 49 which are headed as at 50 and which extend through the bottom of the cup into countersunk'opening 5| in the block 41'. a

In order to provide a. convenient means for rotating the mount from the exterior of the base,

of a set screw 56 therethrough to the end 53 of the screw 52.

Rigid with the upturned rim 5'! of the cup or carrier48.areupstanding spring farms 59 which are of spring metal. In the embodiment herein, four such arms are shown, although more or less could be used. The arms 59 are preferably affixed to rim 5! as by rivets 58 although they might be integral therewith. The upper end of each of the spring arms has a pair of laterally extending ears 60 which clamp the upwardly extending link 6| therebetween. The length-of: the spring arm 59 and its associated contact or link 5| is such that the link 5| will reach above the bottom edge 64 of the cam guide 4|, and when the mount is rotated by knob 55 the link 6| that faces the stop 44 will be cammedinwardly by cam guide 4| to tense the associated spring arm59 and force link 6| into said stop. The link is of fusible metal and preferably is square in cross section, as shown in Fig. 4, to correspond was substan'-' tially U-shaped contact 'or' stop" portion 44 at the As shown in Fig. '2, stop 44 is inclined slightly so that when link 6| is cammed therein by cam guide 4|, the entire inner face of the stop "44 will be in contact :with

link 5| at the end of the now inclined and flexed arm 59 thereof.

A resilient contact arm 65 is affixed at one end terminal post 40 as at 66 and is in electrical contact at its free end 6'! with the metal cup'48. In order to limit the rotation offth'e mount to one direction only, block 41 is preferably provided with a plurality of ratchet teeth 69 on the'periphery thereof which coact with ratchet pawl "I0 pivoted'at H to the bottom plate I3 and resiliently I w the block 41 by In the embodiment herein, foururged against the periphery of spring 12.

ratchet teeth are shown on'the block correspond ing at least to the number of spring arms 59 and equally spaced therefrom but a-greater number could be used if desiredfi With a link 5| in stop 44, as shown in Figs.'2

arid 4, the container I0 -is filled with liquid and a source of current'is applied to terminalp'lugs38 I and 40. The circuit is from terminal plug 38, lead 31, heatingelemen't 28, bolt 33, cam guide 4|, contact 44, link 5|,'spring arm 55, metal cup 43, contact arm 65'to the other terminal. Since a good heat conducting path is established from I the source'of heat to the metal stop 44, overheating (as for instance inthe absence ofliq'uid) will cause the engaged link 6| to soften. Before the fusible link melts, its mechanical strength will have been so greatly reduced that itwillbe sheared under the tension of the spring arm 55 which will snap 'outwardly'pthreby breaking the circuit so rapidly that there is no danger of arc: mg.

But for this mechanical shearing action, if the user should cut on theelectric current when the fusible link had just begun to soften and had been deformed from its original shape, it would remain in this deformed condition When'the-ap-f paratus was permitted to cool to normal temperature. Thedeforinity of the link might cause only slight contact to be m'adebetweenthe link a Joint which upon passage of current therethrough upon further use of the appliance might cause suflicient heat to develop at the point of contact to-melt the link even though the-container was full of water and the appliance operating normally.

i As the-links other than the one in operation, are not in contact with any heat conducting metal such as the stop 44, although the temperature in the base will rise due to overheating in container I I, this rise will not be sufficient to weaken them before the circuit is broken by the rupture of the link in operative position.

The user, noticing that the device is not operating, will turn knob 55 to again complete the heating circuit. As the link that formerly had been in contact has been sheared, there is nothing to impede the clockwise rotation of the knob 55, as shown in Figs. 1 and 2. When the knob is turned in a clockwise direction, link 6! will first abut against the leading edge of the cam arm 42 and be thereby forced inwardly against the tension of spring arm 59.

As the knob is rotated further, the link will ride over the bend 43 in the cam arm and then snap into contact 44. It is to be noted that even when link 6| is seated in contact 44, the spring arm 59 will still be tensed, thereby retaining the link m the contact. The configuration of thecontact and the link will thereupon prevent any further rotation of the knob and a positive contact will be made that will not jar loose.

In the embodiment shown in Fig. '7, similar parts have their reference numerals primed. In this embodiment an insulated post 15 is provided rigid with the carrier 48' and extending upright therefrom at the axis thereof. Affixed to the upper end of the insulated post 15, as by a screw T6, is a spider H having a plurality of radiating arms '78 of conducting material, each of which is aligned with one of the spring arms 59' and so spaced therefrom that when the spring arms 59' are in upright position they will not engage the arms 18 and when a spring arm 59 has been carried inwardly and tensed by cam guide 4|, it will contact the end of an arm 18 as at 19. End

29" of resistance wire 28" extends throu h a bore- 80 in ledge 21 and insulating mount 22', and is connected by a lead 82 to spider Tl.

The embodiment shown in Fig. 7 operates in a manner similar to that of Figs. 1 to 6 exceptfcr the fact that the fusible link serves as a retaining device for holding a spring arm 59' and con ducting arm 18 in contact, but no current passes therethrough. Under excessive heat, link Bi will soften and the tension of spring arm 59 will cause the latter to snap outwardly, sheathing the now soft link 6i and thereby breaking the contact between arm l8 and spring arm 59'. When cup 48' is rotated, and link 6| with its associated spring arm" 59" is urged inwardly by cam guide 4|", the spring arm will engage its associated contacting arm 18' to make contact therewith, thereby completing the circuit to the source of current as from lead 31', resistance cone 28, lead 82 to spider [1, arm [8, spring arm 59, cup 48' and spring contact arm 65'.

Thus by the device hereinabove described, an eflicient protective device is provided that will positively break the circuit in the event ofany overheating, yet can quickly and simp y be ad-' justed to restore the appliance to operative conditi'on without the need for special skill or any tools.

When all the fusible links have been melted," it is a relativelysimple matter to remove the bottom plate 13 by unloosing screws l4. The entire carrier unit canthen be replaced by a new unit or the arms 60 at the ends of the spring arm 59 may be spread apart, the stubs of the old links removed and new links installed with only the use of a pair of pliers.

As many changes could be made in the above construction, and many apparently widely dif-' ferent embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention what I claim as new and desire to secure by Letters- Patent of the United States is: 1

l. A protective device for electric heating appliances, said device comprising a mount having a plurality of spring thereon, a fusiblelink at the end of each of said spring arms, a contact of heat conducting material, a cam associated with said contact, means to sheet relative movement of the contact and the fusible links for abutment-of one of said links against said cam to guide said link along said cam into engagement with said contact to maintain the associated arm in circuit and to tense said arm, whereupon the arm will be snapped out of cir-- cuit by weakening of the engaged link.

2. A protective device for electric heating appliances, said device comprising, a rotatable mount, a plurality of spring arms rotatable with said mount, a fusible link at the end of each of said spring arms, a fixed contact of heat con ducting material normally out of the path of rotation of said fusible links, and means associated with said fixed-contact and in the path of rotation of said fusible links after rupture of the engaged link to bring the next fusible link into engagement with said iixed contact to maintain the correspondingspring arm in circuit and to tense said spring arm, whereupon the arm willbe snapped out of circuit by weakening of the engaged link.

3. A protective device for electric heating appliances, said device comprising a rotatable block, a plurality of spring arms rotatable with said block, a fusible link at the end of each of; said spring arms, afixed contact of heat-com ducting material normally out of the path of rotation of said fusible links, and a cam guide associated with said fixed contact and in the path of rotation of said fusible links successively- 5. A resettable protective device for electric heating appliances, said device comprising a rotatable insulating block, a carrier afiixed to said block, a plurality, of spring arms rigid with said carrier and rotatable therewith, a fusible.

link at the end of each of said spring arms, a"-

fixed contact of, heat conducting material normally out of the'path of rotation of said fusible.

links,and a cam guide associated with said atfixed contact and in the path of rotation of said fusible links successively to bring said links into engagement with said fixed contact to maintain the corresponding spring-arm in circuit and to stress said spring arm, whereupon the arm will be snapped out of circuit by weakening of the engaged link.

6. A resettable protective device for electric heating appliances, said device comprising a rotatable insulating block, a carrier affixed to said block, a plurality of spring arms rigid with said carrier and rotatable therewith, a fusible 'link at the end of each of said spring arms, a

fixed contact of heat conducting material engaged by one of said links and maintaining the corresponding arm in'circuit and normally out of the path of rotation of said fusible links, a cam arm unitary with said fixed contact and in the path of rotation of said fusible links, successively to deflect each of said spring arms inwardly to stress the latter and to bring its as sociated link into engagement with said fixed contact, the tension of said spring arm thereby aiding in retaining said link in said contact.

'7. A resettable protective device for an electrical unit of the type having a heating element, said device comprising a rotatable insulating block, a metal cup shaped carrier affixed to said block, a plurality of spring arms aflixed at one end to the rim of said cup, a fusible link at the free end of each of said spring arms, a cam guide of heat conducting metal in electrical circuit with such heating element and in the path of rotation of said fusible links, a substantially U-shaped contact unitary with said cam guide at one end thereof and normally out of the path of rotation of said fusible links, and means to rotate said block and said carrier, thereby successively to bring each of said links intocontact with said cam guide to deflect each of said spring arms inwardly and to cam said link into engagement with said contact.

8. The combination set forth in claim 7 in which means are provided, resiliently urged against the rim of said metal cup shaped carrier to make contact therewith.

9. The combination set forth in claim I in which said fusible link and said U-shaped contact are substantially square in cross section, thereby to retain said link in said contact under the tension of said deflected spring arm.

10, A resettable protective device for an electrical unit of the type having a heating element, said device comprising a rotatable insulating block, a metal cup shaped carrier afhxed to said block, a plurality of spring arms aihxed at one end to the rim of said cup and rotatable there-- with, a fusible link at the free end of each of said springarms, a cam guide of heat conducting metal in electrical circuit with such heating element and in the path of rotation of such fusible links, a substantially U-shaped contact unitary with said cam guide at one end thereof and normally out of the path of rotation of said fusible links, and means resiliently urged against the rim of said cup shaped carrier to, make contact therewith, means to rotate said block and said carrier, thereby successively to deflect each of said spring arms inwardly and to cam the link thereof into engagement with said contact, and ratchet means coacting with said block and said carrier to limit the direction of rotation thereof.

11. A resettable protective device for an elec trical appliance of the type having a base, a bot tom plate, a heating element afiixed to the top of said base and terminal plugs for connecting a source of current to such heating element, said device comprising an insulating block rotatably mounted on such bottom plate, a cup shaped carrier afiixed to said block and rotatable therewith, a plurality of spring arms rigid with said carrier at the rim thereof and rising therefrom, a fusible link at the end of each of said spring arms, a cam guide including a contact, electrically connected to one end of such heating element and depending from the top of such base in the path of rotation of said fusible links, and a contact arm amxed at one end to one of such plugs and having its free end resiliently urged against the rim of said cup shaped carrier to make contact therewith.

12. A resettable protective device for an electrical appliance of the type comprising a base, a bottom plate aifixed thereto, a heating element afiixed to the top of said base and terminal plugs for connecting a source of current to such heating element, said device comprising an insulating block, a metal cup shaped carrier afiixed to said block, means rigid with said block and passing through such bottom plate for manually rotating said biock'and said carrier, means on such bottom plate coacting with said block to limit the rotation thereof, a plurality of spring arms rigid with said carrier and rising upwardly therefrom, a fusible link affixed to the free end of each of said spring arms, a contact connected to one end of such heating element and depending from the top of such base, means associated with said contact and in the path of ro-,

tation of said fusible links successively to cam said spring arms inwardly, thereby tensing the same as said block is rotated and successively moving said links into engagement with said contact, the tensed spring arm thereupon aiding in retaining said link in engagement with said contact, and a contact arm aiiixed atone end to one of such terminal plugs and having its free end urged against the rim of said cup shaped carrier.

13. The combination set forth in claim 12 in which the means on such bottom plate coacting with said block to limit the rotation thereof comprises a plurality of ratchet teeth on said block at the periphery thereof and a ratchet pawl pivotally mounted on such bottom plate and resiliently urged against the periphery of said block.

14. A resettable protective device for an electrical appliance of the type comprising a, base, a bottom plate affixed thereto, a heating element and terminal plugs for connecting a source of current to such heating element, a substantially. cylindrical insulating mount affixed to the top of such base, extending through an opening therein, and supporting such heating element, a substantially cylindrical casing affixed to such base and encompassing such heating element, and a bolt extending through an opening in such mount, connected at its upper end to one end of such heating element and protruding from such mount at its lower end, said device comprising a cam guide affixed to the protruding end of such bolt, an insulating block, a metal cup shaped carrier aiiixed to said block, means rigid with said block and passing through such bottom plate for manually rotating said block and said carrier, a plurality of spring arms rigid with said carrier and rising upwardly therefrom, a fusible link affixed to the end of each of said spring arms, the path of rotation of said spring arms and said links causing said links successively to abut against said cam guide, thereby urging said spring arms inwardly, a sto on said cam guide to retain said link in contact therewith and a contact arm affixed at one end to one of such 9 terminal plugs and having its free end urged Number against the rim of said cup shaped carrier. 1,839,329 EMIL KOLISCH. 1,848,449 1,848,924 REFERENCES CITED 5 1,910,933 The following references are of record in the 38 file of this pafltent: I

UNITED STATES PATENTS Number Number Name Date 1 13,984 495,038 Hill Apr. 11, 1893 of 1904 1,496,907 schury June 10, 1924 Name Date Murphy Jan. 5, 1932 Wiegand Mar. 8, 1932 Ammerman Mar. 8, 1932 Santurello May 23, 1933 Larsen Jan. 23, 1934 FOREIGN PATENTS Country Date Great Britain June 8, 1905 

